OpenRaiser/Intern-Atlas huggingface dataset:
Enhanced Location Based Routing Protocol for 6LoWPAN
Venue: arXiv cs.NI 2012
Year: 2012

6LoWPAN (IPv6 over IEEE 802.15.4) standardized by IEEE 802.15.4 provides IP communication capability for nodes in WSN. An adaptation layer is introduced above the MAC layer to achieve header compression, fragmentation and reassembly of IP packets. The location-based information is used to simplify the routing policy. This paper proposes an efficient location-based routing protocol, considering link quality and distance between nodes as the routing metric. The proposed Enhanced Location-based routing protocol (ELBRP) was simulated in NS2 version 2.32 and performance were analysed in terms of packet delivery ratio, throughput and average end-to-end delay. From the results obtained, it is found that the proposed ELBRP outperforms existing LOAD protocol.
Session level analysis of P2P television traces
Venue: arXiv cs.NI 2012
Year: 2012

In this study we examine statistical properties of traffic generated by the popular P2P IPTV application SopCast. The analysis aims at a better understanding of the mechanisms used by such applications and their impact on the network. Since the most popular P2P IPTV applications use proprietary unpublished protocols, we look directly at the generated traffic focusing on a single session analysis, which is the major contribution of our work. We present a basic characterisation of the traffic profile generated by SopCast during every separate session in terms of the intensity, the burstiness, the distribution of the packet sizes and the correlation. We show that some of these statistical properties of the analysed traffic may be quite different depending on the particular session.
Frozen variables in random boolean constraint satisfaction problems
Venue: arXiv cs.DM 2012
Year: 2012

We determine the exact freezing threshold, r^f, for a family of models of random boolean constraint satisfaction problems, including NAE-SAT and hypergraph 2-colouring, when the constraint size is sufficiently large. If the constraint-density of a random CSP, F, in our family is greater than r^f then for almost every solution of F, a linear number of variables are frozen, meaning that their colours cannot be changed by a sequence of alterations in which we change o(n) variables at a time, always switching to another solution. If the constraint-density is less than r^f, then almost every solution has o(n) frozen variables. Freezing is a key part of the clustering phenomenon that is hypothesized by non-rigorous techniques from statistical physics. The understanding of clustering has led to the development of advanced heuristics such as Survey Propogation. It has been suggested that the freezing threshold is a precise algorithmic barrier: that for densities below r^f the random CSPs can be solved using very simple algorithms, while for densities above r^f one requires more sophisticated techniques in order to deal with frozen clusters.
The arithmetic complexity of tensor contractions
Venue: arXiv cs.CC 2012
Year: 2012

We investigate the algebraic complexity of tensor calulus. We consider a generalization of iterated matrix product to tensors and show that the resulting formulas exactly capture VP, the class of polynomial families efficiently computable by arithmetic circuits. This gives a natural and robust characterization of this complexity class that despite its naturalness is not very well understood so far.
ReDS: A Framework for Reputation-Enhanced DHTs
Venue: arXiv cs.NI 2012
Year: 2012

Distributed Hash Tables (DHTs) such as Chord and Kademlia offer an efficient solution for locating resources in peer-to-peer networks. Unfortunately, malicious nodes along a lookup path can easily subvert such queries. Several systems, including Halo (based on Chord) and Kad (based on Kademlia), mitigate such attacks by using a combination of redundancy and diversity in the paths taken by redundant lookup queries. Much greater assurance can be provided, however. We describe Reputation for Directory Services (ReDS), a framework for enhancing lookups in redundant DHTs by tracking how well other nodes service lookup requests. We describe how the ReDS technique can be applied to virtually any redundant DHT including Halo and Kad. We also study the collaborative identification and removal of bad lookup paths in a way that does not rely on the sharing of reputation scores --- we show that such sharing is vulnerable to attacks that make it unsuitable for most applications of ReDS. Through extensive simulations we demonstrate that ReDS improves lookup success rates for Halo and Kad by 80% or more over a wide range of conditions, even against strategic attackers attempting to game their reputation scores and in the presence of node churn.
A Connected Enterprise - Transformation through Mobility and Social Networks
Venue: arXiv cs.OH 2012
Year: 2012

Due to rapid changes in business dynamics, there is a growing demand to encourage social conversations/exchanges and the ability to connect and communicate with peers, partners, customers and other stakeholders anytime, anywhere which drives the need of mobile-enable, the existing enterprise applications. This paper highlights a distinct set of needs and key customer challenges that must be considered and addressed for deployment of Social Collaboration applications and Mobility services in enterprises. It not only addresses the Critical Success Factors for enterprise mobility enablement but also outlines the unique business requirements to rapidly create social collaboration culture and the discipline of turning social data into meaningful insights to drive business decisions in real-time. Moreover, the paper emphasizes on developing composite offerings on social enterprise and Mobile networks that not only offer the value proposition in terms of financially oriented results, but also help customer to maximize return on investment (ROI).
Monitoring Control Updating Period In Fast Gradient Based NMPC
Venue: arXiv cs.SY 2012
Year: 2012

In this paper, a method is proposed for on-line monitoring of the control updating period in fast-gradient-based Model Predictive Control (MPC) schemes. Such schemes are currently under intense investigation as a way to accommodate for real-time requirements when dealing with systems showing fast dynamics. The method needs cheap computations that use the algorithm on-line behavior in order to recover the optimal updating period in terms of cost function decrease. A simple example of constrained triple integrator is used to illustrate the proposed method and to assess its efficiency.
Streaming Complexity of Checking Priority Queues
Venue: arXiv cs.DS 2012
Year: 2012

This work is in the line of designing efficient checkers for testing the reliability of some massive data structures. Given a sequential access to the insert/extract operations on such a structure, one would like to decide, a posteriori only, if it corresponds to the evolution of a reliable structure. In a context of massive data, one would like to minimize both the amount of reliable memory of the checker and the number of passes on the sequence of operations. Chu, Kannan and McGregor initiated the study of checking priority queues in this setting. They showed that use of timestamps allows to check a priority queue with a single pass and memory space O(N^(1/2)), up to a polylogarithmic factor. Later, Chakrabarti, Cormode, Kondapally and McGregor removed the use of timestamps, and proved that more passes do not help. We show that, even in the presence of timestamps, more passes do not help, solving a previously open problem. On the other hand, we show that a second pass, but in reverse direction, shrinks the memory space to O((log N)^2), extending a phenomenon the first time observed by Magniez, Mathieu and Nayak for checking well-parenthesized expressions.
Kinetic energy preserving and entropy stable finite volume schemes for compressible Euler and Navier-Stokes equations
Venue: arXiv cs.NA 2012
Year: 2012

Centered numerical fluxes can be constructed for compressible Euler equations which preserve kinetic energy in the semi-discrete finite volume scheme. The essential feature is that the momentum flux should be of the form $f^m_\jph = \tp_\jph + \avg{u}_\jph f^ρ_\jph$ where $\avg{u}_\jph = (u_j + u_{j+1})/2$ and $\tp_\jph, f^ρ_\jph$ are {\em any} consistent approximations to the pressure and the mass flux. This scheme thus leaves most terms in the numerical flux unspecified and various authors have used simple averaging. Here we enforce approximate or exact entropy consistency which leads to a unique choice of all the terms in the numerical fluxes. As a consequence novel entropy conservative flux that also preserves kinetic energy for the semi-discrete finite volume scheme has been proposed. These fluxes are centered and some dissipation has to be added if shocks are present or if the mesh is coarse. We construct scalar artificial dissipation terms which are kinetic energy stable and satisfy approximate/exact entropy condition. Secondly, we use entropy- variable based matrix dissipation flux which leads to kinetic energy and entropy stable schemes. These schemes are shown to be free of entropy violating solutions unlike the original Roe scheme. For hypersonic flows a blended scheme is proposed which gives carbuncle free solutions for blunt body flows. Numerical results for Euler and Navier-Stokes equations are presented to demonstrate the performance of the different schemes.
A Bayesian Nonparametric Approach to Image Super-resolution
Venue: arXiv cs.LG 2012
Year: 2012

Super-resolution methods form high-resolution images from low-resolution images. In this paper, we develop a new Bayesian nonparametric model for super-resolution. Our method uses a beta-Bernoulli process to learn a set of recurring visual patterns, called dictionary elements, from the data. Because it is nonparametric, the number of elements found is also determined from the data. We test the results on both benchmark and natural images, comparing with several other models from the research literature. We perform large-scale human evaluation experiments to assess the visual quality of the results. In a first implementation, we use Gibbs sampling to approximate the posterior. However, this algorithm is not feasible for large-scale data. To circumvent this, we then develop an online variational Bayes (VB) algorithm. This algorithm finds high quality dictionaries in a fraction of the time needed by the Gibbs sampler.
Creation of Digital Test Form for Prepress Department
Venue: arXiv cs.CV 2012
Year: 2012

The main problem in colour management in prepress department is lack of availability of literature on colour management and knowledge gap between prepress department and press department. So a digital test from has been created by Adobe Photoshop to analyse the ICC profile and to create a new profile and this analysed data is used to study about various grey scale of RGB and CMYK images. That helps in conversion of image from RGB to CMYK in prepress department.
Un modèle de trafic adapté à la volatilité de charge d'un service de vidéo à la demande: Identification, validation et application à la gestion dynamique de ressources
Venue: arXiv cs.NI 2012
Year: 2012

Dynamic resource management has become an active area of research in the Cloud Computing paradigm. Cost of resources varies significantly depending on configuration for using them. Hence efficient management of resources is of prime interest to both Cloud Providers and Cloud Users. In this report we suggest a probabilistic resource provisioning approach that can be exploited as the input of a dynamic resource management scheme. Using a Video on Demand use case to justify our claims, we propose an analytical model inspired from standard models developed for epidemiology spreading, to represent sudden and intense workload variations. As an essential step we also derive a heuristic identification procedure to calibrate all the model parameters and evaluate the performance of our estimator on synthetic time series. We show how good can our model fit to real workload traces with respect to the stationary case in terms of steady-state probability and autocorrelation structure. We find that the resulting model verifies a Large Deviation Principle that statistically characterizes extreme rare events, such as the ones produced by "buzz effects" that may cause workload overflow in the VoD context. This analysis provides valuable insight on expectable abnormal behaviors of systems. We exploit the information obtained using the Large Deviation Principle for the proposed Video on Demand use-case for defining policies (Service Level Agreements). We believe these policies for elastic resource provisioning and usage may be of some interest to all stakeholders in the emerging context of cloud networking.
A new edge selection heuristic for computing the Tutte polynomial of an undirected graph
Venue: arXiv cs.DM 2012
Year: 2012

We present a new edge selection heuristic and vertex ordering heuristic that together enable one to compute the Tutte polynomial of much larger sparse graphs than was previously doable. As a specific example, we are able to compute the Tutte polynomial of the truncated icosahedron graph using our Maple implementation in under 4 minutes on a single CPU. This compares with a recent result of Haggard, Pearce and Royle whose special purpose C++ software took one week on 150 computers.
Ranking Search Engine Result Pages based on Trustworthiness of Websites
Venue: arXiv cs.DB 2012
Year: 2012

The World Wide Web (WWW) is the repository of large number of web pages which can be accessed via Internet by multiple users at the same time and therefore it is Ubiquitous in nature. The search engine is a key application used to search the web pages from this huge repository, which uses the link analysis for ranking the web pages without considering the facts provided by them. A new algorithm called Probability of Correctness of Facts(PCF)-Engine is proposed to find the accuracy of the facts provided by the web pages. It uses the Probability based similarity function (SIM) which performs the string matching between the true facts and the facts of web pages to find their probability of correctness. The existing semantic search engines, may give the relevant result to the user query but may not be 100% accurate. Our algorithm computes trustworthiness of websites to rank the web pages. Simulation results show that our approach is efficient when compared with existing Voting and Truthfinder[1] algorithms with respect to the trustworthiness of the websites.
Recent Trends of Measurement and Development of Vibration Sensors
Venue: arXiv cs.SY 2012
Year: 2012

In recent trends, sensors are devices which monitor a parameter of a system, hopefully without disturbing that parameter. Vibration measurement has become an important method in mechanical structural products research, design, produce, apply and maintenance. Vibration sensor is more and more important as key devices. Nowadays, with the development of computer technology, electronic technology and manufacturing process, a variety of vibration sensors have come forth in succession.
A Coherent Distributed Grid Service for Assimilation and Unification of Heterogeneous Data Source
Venue: arXiv cs.DB 2012
Year: 2012

Grid services are heavily used for handling large distributed computations. They are also very useful to handle heavy data intensive applications where data are distributed in different sites. Most of the data grid services used in such situations are meant for homogeneous data source. In case of Heterogeneous data sources, most of the grid services that are available are designed such a way that they must be identical in schema definition for their smooth operation. But there can be situations where the grid site databases are heterogeneous and their schema definition is different from the central schema definition. In this paper we propose a light weight coherent grid service for heterogeneous data sources that is very easily install. It can map and convert the central SQL schema into that of the grid members and send queries to get according results from heterogeneous data sources.
Rough sets and matroidal contraction
Venue: arXiv cs.AI 2012
Year: 2012

Rough sets are efficient for data pre-processing in data mining. As a generalization of the linear independence in vector spaces, matroids provide well-established platforms for greedy algorithms. In this paper, we apply rough sets to matroids and study the contraction of the dual of the corresponding matroid. First, for an equivalence relation on a universe, a matroidal structure of the rough set is established through the lower approximation operator. Second, the dual of the matroid and its properties such as independent sets, bases and rank function are investigated. Finally, the relationships between the contraction of the dual matroid to the complement of a single point set and the contraction of the dual matroid to the complement of the equivalence class of this point are studied.
Consistent Layout for Thematic Software Maps
Venue: arXiv cs.SE 2012
Year: 2012

Software visualizations can provide a concise overview of a complex software system. Unfortunately, since software has no physical shape, there is no "natural" mapping of software to a two-dimensional space. As a consequence most visualizations tend to use a layout in which position and distance have no meaning, and consequently layout typical diverges from one visualization to another. We propose a consistent layout for software maps in which the position of a software artifact reflects its \emph{vocabulary}, and distance corresponds to similarity of vocabulary. We use Latent Semantic Indexing (LSI) to map software artifacts to a vector space, and then use Multidimensional Scaling (MDS) to map this vector space down to two dimensions. The resulting consistent layout allows us to develop a variety of thematic software maps that express very different aspects of software while making it easy to compare them. The approach is especially suitable for comparing views of evolving software, since the vocabulary of software artifacts tends to be stable over time.
Learning Price-Elasticity of Smart Consumers in Power Distribution Systems
Venue: arXiv cs.IT 2012
Year: 2012

Demand Response is an emerging technology which will transform the power grid of tomorrow. It is revolutionary, not only because it will enable peak load shaving and will add resources to manage large distribution systems, but mainly because it will tap into an almost unexplored and extremely powerful pool of resources comprised of many small individual consumers on distribution grids. However, to utilize these resources effectively, the methods used to engage these resources must yield accurate and reliable control. A diversity of methods have been proposed to engage these new resources. As opposed to direct load control, many methods rely on consumers and/or loads responding to exogenous signals, typically in the form of energy pricing, originating from the utility or system operator. Here, we propose an open loop communication-lite method for estimating the price elasticity of many customers comprising a distribution system. We utilize a sparse linear regression method that relies on operator-controlled, inhomogeneous minor price variations, which will be fair to all the consumers. Our numerical experiments show that reliable estimation of individual and thus aggregated instantaneous elasticities is possible. We describe the limits of the reliable reconstruction as functions of the three key parameters of the system: (i) ratio of the number of communication slots (time units) per number of engaged consumers; (ii) level of sparsity (in consumer response); and (iii) signal-to-noise ratio.
Semi-automatic annotation process for procedural texts: An application on cooking recipes
Venue: arXiv cs.AI 2012
Year: 2012

Taaable is a case-based reasoning system that adapts cooking recipes to user constraints. Within it, the preparation part of recipes is formalised as a graph. This graph is a semantic representation of the sequence of instructions composing the cooking process and is used to compute the procedure adaptation, conjointly with the textual adaptation. It is composed of cooking actions and ingredients, among others, represented as vertices, and semantic relations between those, shown as arcs, and is built automatically thanks to natural language processing. The results of the automatic annotation process is often a disconnected graph, representing an incomplete annotation, or may contain errors. Therefore, a validating and correcting step is required. In this paper, we present an existing graphic tool named \kcatos, conceived for representing and editing decision trees, and show how it has been adapted and integrated in WikiTaaable, the semantic wiki in which the knowledge used by Taaable is stored. This interface provides the wiki users with a way to correct the case representation of the cooking process, improving at the same time the quality of the knowledge about cooking procedures stored in WikiTaaable.
Hybrid Approaches to Image Coding: A Review
Venue: arXiv cs.IT 2012
Year: 2012

Nowadays, the digital world is most focused on storage space and speed. With the growing demand for better bandwidth utilization, efficient image data compression techniques have emerged as an important factor for image data transmission and storage. To date, different approaches to image compression have been developed like the classical predictive coding, popular transform coding and vector quantization. Several second generation coding schemes or the segmentation based schemes are also gaining popularity. Practically efficient compression systems based on hybrid coding which combines the advantages of different traditional methods of image coding have also been developed over the years. In this paper, different hybrid approaches to image compression are discussed. Hybrid coding of images, in this context, deals with combining two or more traditional approaches to enhance the individual methods and achieve better-quality reconstructed images with higher compression ratio. Literature on hybrid techniques of image coding over the past years is also reviewed. An attempt is made to highlight the neuro-wavelet approach for enhancing coding efficiency.
Distributing Content Simplifies ISP Traffic Engineering
Venue: arXiv cs.NI 2012
Year: 2012

Several major Internet service providers (e.g., Level-3, AT&T, Verizon) today also offer content distribution services. The emergence of such "Network-CDNs" (NCDNs) are driven by market forces that place more value on content services than just carrying the bits. NCDNs are also necessitated by the need to reduce the cost of carrying ever-increasing volumes of traffic across their backbones. An NCDN has the flexibility to determine both where content is placed and how traffic is routed within the network. However NCDNs today continue to treat traffic engineering independently from content placement and request redirection decisions. In this paper, we investigate the interplay between content distribution strategies and traffic engineering and ask how an NCDN should engineer traffic in a content-aware manner. Our experimental analysis, based on traces from a large content distribution network and real ISP topologies, shows that effective content placement can significantly simplify traffic engineering and in most cases obviate the need to engineer NCDN traffic all together! Further, we show that simple demand-oblivious schemes for routing and placement such as InverseCap and LRU suffice as they achieve network costs that are close to the best possible.